The present invention relates to mobile communication devices and to cellular radio systems comprising at least a mobile telephone center, mobile stations, and a base station which comprises means for establishing a connection to mobile stations situated in its coverage area using radio frequency signals, and telecommunication means for transferring telecommunication signals between the mobile telephone center and the mobile stations. The invention also relates to a radio system base station comprising transmitting means for transmitting radio signals to a mobile station situated within its coverage area and telecommunication means for establishing a telecommunication connection to the mobile telephone center of the system. The invention also relates to a cellular radio system mobile station comprising transmitting means for transmitting radio signals to a base station serving a first radio cell and reception means for receiving radio signals from said base station serving the first radio cell, wherein the reception means comprise means for monitoring a general transmission channel used in said first radio cell for the reception of information transferred by it.
Mobile stations often cause unwanted disturbance in their surroundings. This disturbance can in general be divided into two categories:
interference to electronic devices caused by a mobile station (EMC interference). Such interference is extremely harmful, e.g. in hospitals, airplanes or similar areas, and
disturbance caused to other persons by the ringing tone of a mobile station in public domains or during public occasions (churches, meetings etc.).
The concept referred to below as xe2x80x98mutingxe2x80x99 means, in the present context, that a mobile station is controlled such that it no longer presents a disturbance, or presents a reduced level of disturbance, in its surroundings.
In the prior known mobile communication systems it has not been possible to automatically prevent the occurrence of the disturbances described above. Rather, this responsibility has been left to the user of a mobile station who must remember to turn off his mobile station and/or to adjust its alarm tune to a lower level in order to avoid disturbance. In practice, it has been found that the users of mobile stations do not always remember to turn off their mobile stations or to adjust their buzzers to a lower level.
It is an object of the present invention to overcome or at least mitigate the above described problem and to provide a method for eliminating or reducing the disturbance caused by a mobile station situated in a certain area. This object is achieved by the use of the method according to the invention, characterized in that a mobile station is provided with control means for muting the mobile station in response to a predetermined message transmitted to the mobile station, and transmitting means is arranged in said certain area for transmitting said predetermined message to the mobile station situated in the area in order to mute
According to a first aspect of the present invention there is provided a method of operating a mobile station in an RF telephone network in order to reduce or eliminate disturbance by the phone in a local area of the network whilst allowing the phone to function normally elsewhere in the network, the method comprising:
broadcasting a predefined message across said local area from a base station located within the local area;
detecting the broadcast message at the mobile station when the mobile station enters or otherwise becomes active in the local area; and
in response to detection of the broadcast message, muting the mobile station.
Embodiments of the invention make use of the concept that, when a radio transmitter is arranged in an area where it is important to prevent disturbance and where the transmitter has been arranged to transmit a muting message to all mobile stations arriving in its coverage area, it can be ensured that in said area mobile stations will not cause disturbance even if their users should forget to turn off or mute the alarm tune in their mobile stations on arrival in the area. Case by case, using a muting message, a maximum transmitting output allowed or alternatively a maximum volume for the alarm tune can be signaled to a mobile station. The most significant advantage of this method is accordingly that the disturbance from mobile stations within a certain area can be prevented securely, reliably and automatically, or in other words, without requiring any action by the user of a mobile station.
According to another aspect of the present invention, there is provided a cellular radio system which comprises at least one mobile station comprising control means for muting it in response to a predetermined muting message received by radio communication, and at least one base station comprising means for transmitting said muting message to a mobile station situated within its coverage area.
When an area, in which disturbances caused by mobile stations are wanted to be prevented, is provided with an individual radio cell and a base station serving it, the mobile stations arriving in the area can be forced to monitor the general transmission channel of the cell concerned, over which channel a muting message is transmitted to them. If required, it is possible to force mobile stations situated within the area to lock on to the radio cell in question.
When a base station in a preferred embodiment of the system comprises means for announcing a highest allowed transmitting output to a mobile station using a muting message, and the control means of the mobile station have been arranged to adjust the transmitting output of the transmitter of the mobile station in response to the information comprised in the muting message, it can be ensured that even call attempts made by the user of the mobile station will not cause disturbance. In other words, the transmitting output can be ordered to such a low level (even down to zero) that it will not cause interference to electrical equipment in the environment.
In another preferable embodiment of the system according to the invention, the system (e.g. a mobile communication center) prevents, using a muting message, the connecting of a call directed to a muted mobile station and instead transmits a message advising of the blocked call to the mobile station. The message can in such a case comprise for example an A-subscriber code, allowing the user to find out who has tried to call him. This embodiment naturally requires that a message has been transferred to the mobile communication center informing that the mobile station in question has been muted using a muting message.
According to another aspect of the present invention there is provided a base station which comprises means for transmitting by radio a predetermined muting message to a mobile station situated within its radio coverage area.
In a preferred embodiment of such a base station, the base station comprises monitoring means for the monitoring of predetermined frequency channels, in which case the frequency channels to be monitored include in addition to the frequency channels used by the base station itself, also the frequency channels of adjacent base stations, for example those of the base station of another operator and/or frequency channels used by another radio system. When the base station detects a mobile station transmitting radio signals on a frequency channel, it transmits a muting signal to the mobile station in question, preferably using the BCCH-channel used by the radio system in question. This embodiment facilitates that disturbances within a certain area can be prevented using one base station, instead of needing several base stations in the area concerned. In other words, the base station arranged in the area is adapted to monitor the frequency channels used by, e.g. GSM-, DCS 1800- and DCS 1900-systems, for the detecting and muting of active mobile stations. The application of this embodiment requires that a detected mobile station is capable of receiving signals transmitted on a BCCH-channel used by the system even when it is on a traffic channel, or when the mobile station is making a call.
According to a further aspect of the invention, there is provided a mobile station which comprises control means responding to reception means for muting the mobile station in response to a predetermined muting message. In a preferred embodiment of a mobile station according to the invention, the mobile station comprises means for monitoring signals transmitted by at least two base stations on a general transmitting channel and detecting means for the detection of said muting message on any of said general transmitting channels. In this case, e.g. two base stations with overlapping coverage areas or two different cellular radio systems, it can be ensured that the mobile stations of both systems are muted.
Preferred embodiments of the method, the cellular radio system, the base station and the mobile station according to the invention are characterized in the dependent claims 3 to 6, 8 to 9 and 11 to 14 below.